In increasing soybean production, an important role is given to reducing indirect losses from grain crushing, which adversely affect the quality of seeds, especially when harvesting and processing crops. The impossibility of achieving the optimal mode of operation of the combine at soybean harvesting is due to the peculiarity of the physical and mechanical properties of soybeans. The purpose of the research is to increase the efficiency of the soybean grain harvesting technology based on the development of adapting devices to the combine to obtain the maximum yield of the first fraction of high-quality seeds, followed by their use in sowing without part-time processing (except for pre-sowing etching). The studies were carried out using the modernized Yenisei-1200 combine during the harvesting period 2021-2022 on the experimental field of the Federal State Budgetary Institution of the Federal Research Center of the All-Russian Research Institute of Soybeans. Modernization of the combine makes it possible to collect 60% of high-quality soybean seeds with a low content of weed impurity in a separate section of its bunker. Ripened soybean seeds are soaked in soft modes of operation of the first threshing drum, a separate collection of which increases field germination and biological yield of the first seed fraction. Application of sieves of upper sieve mill of combine harvester cleaning with increased length of blinds petals up to 70 mm together with increased air flow ensures purity of seeds of the first fraction at the level of the first class of sowing standard. Mechanical damage to soybean seeds of the first fraction, which is 4.2%, does not exceed the established standard for crushing and microdepositing combines (5%). The use of seeds of the first fraction in sowing without additional processing reduces the indirect losses of soybeans and, accordingly, the costs of seed production.Ripened soybean seeds are soaked in soft modes of operation of the first threshing drum, a separate collection of which increases field germination and biological yield of the first seed fraction. Application of sieves of upper sieve mill of combine harvester cleaning with increased length of louver petals up to 70 mm together with increased air flow ensures purity of seeds of the first fraction at the level of the first class of sowing standard. Mechanical damage to soybean seeds of the first fraction, which make 4.2%, does not exceed the established standard for crushing and micro damage combines (5%). Using the seeds of the first fraction in sowing without working, reduces indirect losses of soybeans and, accordingly, the costs of seed production.
